1. Field of the Invention
The present invention relates to an ion implantation method and an ion implantation apparatus.
2. Description of the Related Art
In a semiconductor production process, a step (hereinafter, referred to as an “ion implantation step”) of implanting ions to a semiconductor wafer is generally performed for the purpose of changing the conductivity and the crystalline structure of the semiconductor wafer. An apparatus that is used in the ion implantation step is called an ion implantation apparatus, and has a function of forming an ion beam ionized by an ion source and accelerated and a function of transporting the ion beam to an implantation processing chamber and irradiating the ion beam to a wafer inside the processing chamber.
In order to implant ions into an entire surface of a wafer as a processing target, a beam scanner scans an ion beam in a reciprocating manner while reciprocating the wafer in a direction perpendicular to the beam scanning direction. At this time, it is possible to control the amount of the ion beam irradiated to each point of the wafer by changing a beam scanning speed or a reciprocating speed in accordance with the irradiation position on the wafer.
Although it is possible to control the amount of the ion irradiated to each point by changing the beam scanning speed in accordance with each point of the wafer, there is a case in which the amount of the ion irradiated to each point per unit time may be changed by a change in beam scanning speed. Since the amount of the damage for the wafer caused by the implantation of the ion is changed by the ion irradiation amount per unit time, there is a concern that maintenance of a semiconductor production quality may be affected when the ion irradiation amount per unit time changes.